1. Field of the Invention
The present invention relates to a brushless motor having a less turntable for driving media such as CD-ROMs or DVD-ROMs.
2. Description of the Related Art
Referring to FIG. 2, a conventional brushless motor for driving media such as CDs includes a rotor R where a turntable T, which is cut from brass, for accommodating a medium is integrally formed at one side of a rotor case K and a magnet M is formed at the other side of the case K, a shaft J for supporting the rotor R, a housing H for rotatably supporting the shaft J, and a stator ST arranged at one side of the housing H for driving the rotor R.
However, since the turntable T for mounting a medium is formed by a brass cutting process, the cost of materials increases and installation thereof is inconvenient. In particular, since verticality of the shaft J is strictly required to drive a medium such as a CD-ROM, the turntable T for mounting the medium is installed on the shaft J and then the turntable T is cut at right angles with respect to the shaft J. However, although brass is relatively easy to cut, while the shaft J is cut, strength is necessarily brought to the shaft J because brass is metal. Accordingly, when strength applied to firmly hold the turntable T is weak, the shaft J is damaged.
Also, to reduce the cost for production, as shown in FIG. 3, a turntable JT formed of resin is used. However, when the turntable JT is used, accurate mounting is required and a thin leaf spring B pressing the inner circumferential portion of a medium is additionally needed to secure support strength with respect to the media.
To solve the above problems, it is an objective of the present invention to provide a brushless motor having a turntable so that a high-priced turntable formed by cutting brass is not needed and the cost for production can be reduced.
It is another objective of the present invention to provide a brushless motor having a turntable which does not use an additional thin leaf spring to press the inner diameter portion of a medium.
It is yet another objective of the present invention to provide a brushless motor for automatically compensating unbalance of a rotation system with a simple structure.
Accordingly, to achieve the above objectives, there is provided a brushless motor having a turntable including a rotor in which a turntable is integrally formed on the outer side of a rotor case and a magnet is arranged on the inner side thereof, a shaft for supporting the rotor, a stator base for supporting the shaft, and a stator formed on a portion of the stator base for driving the rotor, in which the turntable which has a media mounting portion at least partly formed of resin, includes a media installation guide formed of the same resin to support a medium, and at least one media inner diameter chucking spring member integrally formed of resin to have a diameter slightly greater than the media installation guide and the inner diameter of the media.
It is preferred in the present invention that a ball housing containing mobile balls for compensating unbalance is provided at the turntable opposite to a media mounting surface of the media mounting portion.
It is preferred in the present invention that the turntable is installed at a shaft protruding above the rotor case.
It is preferred in the present invention that the media inner diameter chucking spring member is arranged at a space and a free end thereof protrudes above the media mounting portion.
It is preferred in the present invention that a media slip preventing means is provided on a media mounting surface at least at the outer circumference of the turntable.
It is preferred in the present invention that a media mounting surface of the resin media mounting portion which contacts the medium is cut-processed at right angles with respect to the shaft.